Method for producing alkyl oligoglucoside and alkenyl oligoglucoside carboxylic acid salts with reduced organochloride compounds

ABSTRACT

A process for reducing the amount of halocarbons in a mixture containing water and at least one of an alkyl or alkenyl glycoside carboxylic acid. The amount of halocarbon is reduced by heating the mixture at a temperature of 50° C. to 120° C. at a pH of from 10-14. The amount of organomonochloro compounds can be reduced to a range of 5 ppm or less and the amount of organodichloro compounds can be reduced to a range of 30 ppm.

RELATED APPLICATIONS

This application is filed under 35 U.S.C. § 371 claiming priority fromApplication PCT/EP2003/013920 filed on Dec. 9, 2003, which claimspriority of German patent application DE 102 59 403.1 filed on Dec. 19,2002, the entire contents of each application are incorporated herein byreference.

FIELD OF THE INVENTION

This invention relates generally to surface-active compounds and, moreparticularly, to a new process for the production of special anionicsurfactants which are distinguished by a reduced content of organicchlorine compounds.

BACKGROUND OF THE INVENTION

Carboxylation products of alk(en)yl oligoglycosides are anionicsurfactants which have improved foaming, viscosity and sensoryproperties in relation to the non-derivatized homologs. They arenormally produced by reaction of the glycosides with halocarboxylic acidsalts, especially sodium chloroacetate, in aqueous solution. Some or allof the hydroxyl groups available are reacted, depending upon thequantity of alkylating agent used. Since this reaction generallyrequires an excess of the alkylating agent, the end products alwayscontain traces of organic chlorine compounds which can amount to as muchas 2,000 ppm, based on monochloroacetate for example, or to as much as500 ppm, based on the dichloroacetate present as an impurity in themonochloroacetate.

For cosmetic applications in particular, such quantities oforgano-chlorine compounds are unacceptable because they can causeirritation of the skin or are otherwise undesirable for physiologicalreasons.

Accordingly, the problem addressed by the present invention was toprovide an improved process for the production of alk(en)yloligoglycoside carboxylic acid salts which would give products with acontent of organochlorine compounds of less than 35 ppm and preferablyless than 10 ppm.

BRIEF DESCRIPTION OF THE INVENTION

The present invention relates to a new process for the production ofwater-containing pastes of alkyl and/or alkenyl oligoglycosidecarboxylic acid salts with a reduced content of organochlorinecompounds, characterized in that the alkyl and/or alkenyloligoglycosides are reacted in known manner with halocarboxylic acids orsalts thereof and the reaction products are subjected to an alkalineaftertreatment at temperatures in the range from 50 to 120° C.

It has surprisingly been found that, by subjecting the pastes to analkaline aftertreatment, the overall content of organic chlorinecompounds can be reduced to at least below 35 ppm, and, generally, evento below 10 ppm.

DETAILED DESCRIPTION OF THE INVENTION

Alkyl and/or Alkenyl Oligoglycosides

Alkyl and alkenyl oligoglycosides, which represent one of the twostarting materials for the production of the carboxylic acid salts, areknown nonionic surfactants corresponding to formula (I):R¹O—[G]_(p)  (I)where R¹ is an alkyl and/or alkenyl group containing 4 to 22 carbonatoms, G is a sugar unit containing 5 or 6 carbon atoms and p is anumber of 1 to 10. They may be obtained by the relevant methods ofpreparative organic chemistry.

The alkyl and/or alkenyl oligoglycosides may be derived from aldoses orketoses containing 5 or 6 carbon atoms, preferably glucose. Accordingly,the preferred alkyl and/or alkenyl oligoglycosides are alkyl and/oralkenyl oligoglucosides. The index p in general formula (I) indicatesthe degree of oligomerization (DP), i.e. the distribution of mono- andoligoglycosides, and is a number of 1 to 10. Whereas p in a givencompound must always be an integer and, above all, may assume a value of1 to 6, the value p for a certain alkyl oligoglycoside is ananalytically determined calculated quantity which is generally a brokennumber. Alkyl and/or alkenyl oligoglycosides having an average degree ofoligomerization p of 1.1 to 3.0 are preferably used. Alkyl and/oralkenyl oligoglycosides having a degree of oligomerization of less than1.7 and, more particularly, between 1.2 and 1.4 are preferred from theapplicational point of view.

The alkyl or alkenyl radical R¹ may be derived from primary alcoholscontaining 4 to 11 and preferably 8 to 10 carbon atoms. Typical examplesare butanol, caproic alcohol, caprylic alcohol, capric alcohol andundecyl alcohol and the technical mixtures thereof obtained, forexample, in the hydrogenation of technical fatty acid methyl esters orin the hydrogenation of aldehydes from Roelen's oxosynthesis. Alkyloligoglucosides having a chain length of C₈ to C₁₀ (DP=1 to 3), whichare obtained as first runnings in the separation of technical C₈₋₁₈coconut oil fatty alcohol by distillation and which may contain lessthan 6% by weight of C₁₂ alcohol as an impurity, and also alkyloligoglucosides based on technical C_(9/11) oxoalcohols (DP=1 to 3) arepreferred. In addition, the alkyl or alkenyl radical R¹ may also bederived from primary alcohols containing 12 to 22 and preferably 12 to14 carbon atoms. Typical examples are lauryl alcohol, myristyl alcohol,cetyl alcohol, palmitoleyl alcohol, stearyl alcohol, isostearyl alcohol,oleyl alcohol, elaidyl alcohol, petroselinyl alcohol, arachyl alcohol,gadoleyl alcohol, behenyl alcohol, erucyl alcohol, brassidyl alcohol andtechnical mixtures thereof which may be obtained as described above.Alkyl oligoglucosides based on hydrogenated C_(12/14) coconut oil fattyalcohol having a DP of 1 to 1.8 are preferred.

Halocarboxylic Acids

The carboxyl functions are introduced into the glycosides usinghalocarboxylic acids or salts thereof preferably corresponding toformula (II):Cl(CH₂)_(n)COOX  (II)in which n is a number of 1 to 5 and X is hydrogen or an alkali metal,preferably sodium or potassium. Chloroacetic acid or its sodium salt inparticular is used.Carrying out the Process

The carboxylation of the alk(en)yl oligoglycosides may be carried out inknown manner, i.e. by direct reaction of the reactants in aqueoussolution at elevated temperature. The alkyl and/or alkenyloligoglycosides and the halocarboxylic acids or salts are typically usedin a molar ratio of 1:0.9 to 1:5, preferably in a molar ratio of 1:1.05to 1:3 and more particularly in a molar ratio of 1:1.2 to 1:2. Theexcess of halocarboxylic acids is primarily determined by the number ofcarboxyl functions which are to be introduced into the molecule in thisway. Water-containing pastes of alkyl and/or alkenyl oligoglycosidecarboxylic acid salts with a solids content of 30 to 60 and moreparticularly 40 to 50% by weight and contents of organic chlorinecompounds of up to 2,500 ppm are obtained in this way. For degradation,the pastes are subjected to an alkaline aftertreatment, i.e. areadjusted to a pH of 10 to 14 and preferably 11 to 13 by addition ofaqueous alkali metal compounds, preferably sodium or potassium hydroxidesolution. It has surprisingly been found that the glycoside carboxylicacid salts are not hydrolyzed under these conditions. Anaftertreatment—optionally under (autogenous) pressure—at a temperatureof 60 to 110° C. and more particularly at a temperature of 70 to 90° C.has proved to be particularly advantageous. In addition, it is advisableto carry out the aftertreatment in the absence of atmospheric oxygen,i.e. under an inert gas blanket, in order to prevent discolouration ofthe products. The reaction time depends on the pH and the temperaturetogether and is typically between 2 and 5 hours. It is in fact advisableto follow the progress of the aftertreatment by sampling and toterminate the reaction when the content of monochlorine compounds hasfallen below 5 ppm and the content of dichlorine compounds is below 30ppm.

EXAMPLES Example 1

550 g of a 50% by weight water-containing paste of a C_(12/14) cocoalkyloligoglucoside carboxylate (Plantapon® LGC, Cognis Deutschland GmbH &Co. KG) with a residual content of 314 ppm monochloroacetate and 58 ppmdichloroacetate were introduced into a stirred vessel and adjusted with13.7 g of an aqueous 50% by weight sodium hydroxide solution to a pHvalue of 13.5 (as measured in 10% by weight dilution). The mixture wasthen stirred under nitrogen for 3 h at a temperature of 90 to 95° C. Thepurified product was obtained as a pale yellow liquid and, after thetreatment, had a monochloroacetate content of less than 1 ppm and adichloroacetate content of less than 5 ppm.

Example 2

550 g of a 50% by weight water-containing paste of a C_(12/14) cocoalkyloligoglucoside carboxylate (Plantapon® LGC, Cognis Deutschland GmbH &Co. KG) with a residual content of 314 ppm monochloroacetate and 58 ppmdichloroacetate were introduced into a stirred vessel and adjusted with10.4 g of an aqueous 50% by weight potassium hydroxide solution to a pHvalue of 13.5 (as measured in 10% by weight dilution). The mixture wasthen stirred under nitrogen for 2.5 h at a temperature of 90 to 95° C.The purified product was obtained as a pale yellow liquid and, after thetreatment, had a monochloroacetate content of less than 1 ppm and adichloroacetate content of less than 5 ppm.

1. A process for the preparation of a water containing compositioncomprising at least one member selected from the group consisting ofalkyl oligoglycoside carboxylic acid salts and alkenyl oligoglycosidecarboxylic acid salts with a residual content of halocarbon compoundswhich comprises: heating an aqueous mixture comprising at least onepreformed member selected from the group consisting of alkyloligoglycoside carboxylic acid salts and alkenyl oligoglycosidecarboxylic acid salts, water and residual halocarbon compounds at a pHof from 10 to 14 and a temperature of from 50° to 120° C., whereby amixture with a reduced content of residual halocarbon compounds isformed.
 2. The process of claim 1 which further comprises: (1) reactingan aqueous mixture comprising at least one member selected from thegroup consisting of alkyl oligoglycosides and alkenyl oligoglycosideswith at least one member selected from the group consisting ofhalocarboxylic acids and halocarboxylic acid salts to form an aqueousreaction mixture containing alkyl oligoglycoside carboxylic acid salts,alkenyl oligoglycoside carboxylic acid salts and residual halocarboncompounds; and (2) heating the aqueous reaction mixture at a pH of from10 to 14 to form a heated reaction mixture with a reduced content ofresidual halocarbon compounds.
 3. The process as claimed in claim 2,wherein the alkyl and/or alkenyl oligoglycoside comprises a compositionof the formula:R¹O—[G]_(p)  (I) where R¹ is an alkyl and/or alkenyl group containing 4to 22 carbon atoms, G is a sugar unit containing 5 or 6 carbon atoms andp is a number of 1 to
 10. 4. The process as claimed in claim 3, whereinthe oligoglycoside comprises an alkyl glucoside of the formula (I),wherein R¹ is a C₁₂₋₁₈ alkyl group, G is a glucose residue and p is anumber of 1 to 1.8.
 5. The process as claimed in claim 2, wherein thehalocarboxylic acid or salt thereof comprises a compound of the formula:Cl(CH₂)_(n)COOX  (II) wherein n is a number of 1 to 5 and X is hydrogenor an alkali metal.
 6. The process as claimed in claim 2, wherein thehalocarboxylic acid or halocarboxylic acid salt comprises chloroaceticacid or its sodium salt.
 7. The process as claimed in claim 2, whereinthe alkyl and/or alkenyl oligoglycosides and the halocarboxylic acid orits salt are used in a molar ratio of 1:0.9 to 1:5.
 8. The process asclaimed in claim 1, wherein the aqueous mixture comprises at least onemember selected from the group consisting of alkyl oligoglycosidecarboxylic acid salts and alkenyl oligoglycoside carboxylic salts in aconcentration of 30 to 60% by weight.
 9. The process as claimed in claim1, wherein the pH of the aqueous mixture is adjusted to a range of 10 to14 by addition of aqueous alkali metal compounds.
 10. The process asclaimed in claim 1, wherein the aqueous mixture is heated at atemperature of 70 to 90° C.
 11. The process as claimed in claim 1,wherein the aqueous mixture contains residual organochlorine compoundsand is heated until a content of residual organomonochlorine compoundsis below 5 ppm and a content of residual organodichlorine compounds isbelow 30 ppm.
 12. The process of claim 2, wherein the aqueous reactionmixture of step (1) comprises at least one member selected from thegroup consisting of alkyl oligoglycoside carboxylic acid salts andalkenyl oligoglycoside carboxylic salts in a concentration of 30 to 60%by weight.
 13. The process of claim 2, wherein the pH of the aqueousreaction mixture of step (1) is adjusted to a range of 10 to 14 byaddition of aqueous alkali metal compounds.
 14. The process of claim 2,wherein in step (2) the aqueous reaction mixture is heated at atemperature of 70 to 90° C.
 15. The process of claim 2, wherein theaqueous reaction mixture of step (1) contains residual organo chlorinecompounds and is heated until a content of residual organomonochlorinecompounds is below 5 ppm and a content of residual organodichlorinecompounds is below 30 ppm.
 16. The process of claim 3, wherein theaqueous mixture comprises at least one member selected from the groupconsisting of alkyl oligoglycoside carboxylic acid salts and alkenyloligoglycoside carboxylic salts in a concentration of 30 to 60% byweight.
 17. The process of claim 3, wherein the pH of the aqueousmixture is adjusted to a range of 10 to 14 by addition of aqueous alkalimetal compounds.
 18. The process of claim 3, wherein the aqueous mixtureis heated at a temperature of 70 to 90° C.
 19. The process of claim 3,wherein the aqueous mixture contains residual organo chlorine compoundsand is heated until a content of residual organomonochlorine compoundsis below 5 ppm and a content of residual organodichlorine compounds isbelow 30 ppm.
 20. The process of claim 5, wherein the aqueous mixturecomprises at least one member selected from the group consisting ofalkyl oligoglycoside carboxylic acid salts and alkenyl oligoglycosidecarboxylic salts in a concentration of 30 to 60% by weight.